Undersea communications cable systems are a critical part of today's communications infrastructure. A single optical cable, resting on the ocean floor between continents, may be on average capable of transmitting over 8 million concurrent telephone calls. Because of that high transmission density, the downtime resulting from a fault in the cable or its supporting plant equipment is extremely expensive.
Undersea cable systems, by their nature, require maintenance procedures, maintenance equipment and technician expertise that are different from those required in a terrestrial-based system. For that reason, it is often critical to quickly and efficiently determine whether a fault is located in the undersea cable system or in the supporting backhaul or other equipment.
An undersea cable station includes backhaul plant interfacing equipment and other associated equipment. Repairs to undersea cable faults are typically undertaken at the undersea cable station. Undersea cable stations are frequently located in remote coastal areas that are away from population centers. While undersea cable stations were at one time often manned 24×7 with skilled, on-site technicians, that is no longer the case, and a technician must now be dispatched to the station when a fault alarm is received during unmanned hours. Because of the remote locations of the stations, the dispatch is time-consuming, and extends expensive downtime.
Presently, where a central network operating center for the undersea cable system is employed, the decision-making occurs there. That central point, however, is responsible for all carrier traffic and is slow to react to network troubles. It is furthermore difficult for the network operating center to determine whether a fault is located in the undersea cable system, or is in the backhaul or associated terrestrial equipment (i.e., whether the fault is “wet” or “dry”). That is because the central network operating center for the undersea cable system can only see and control the wet side operations.
95% of the undersea cable systems, however, do not contain a central network operations center. There is no tie-in between facility monitoring on undersea cable networks and facility monitoring on the terrestrial network that feeds into the undersea networks. In such a configuration, there is again no way to distinguish between “wet” and “dry” faults.
In either case, valuable time is wasted in responding to a fault alarm. For example, if a technician is dispatched to the undersea cable station, there is a possibility that it will be discovered that the fault is in the backhaul, and the elapsed travel time to the station has been wasted. Conversely, a technician dispatched to the terrestrial plant may discover that the fault is in the undersea cable system. Dispatching technicians in both directions simultaneously is expensive and confusing.
There therefore remains a need for a cost-effective technique to non-intrusively monitor and diagnose fault alarms in undersea cable systems and the associated terrestrial plant and to do that work quickly.